We discuss extensions to the standard polarization formalism for situations in which all three Cartesian components of the electric field are significant. Standard concepts for paraxial formalism such as the degree of polarization, the Stokes parameters, and the Poincaré sphere have generalizations that are neither unique nor trivial. It is shown that this formalism is particularly useful for the description of wobbling fluorophores in Single Molecule Orientation and Localization Microscopy (SMOLM).

Pushed to their limit, tip-enhanced photoluminescence and electroluminescence can be used to generate sub-molecularly resolved fluorescence maps of individual molecules. Combined with spectral selection and time-correlated measurements, these hyper-resolved fluorescence microscopies allowed us to scrutinize the vibronic and charged states of individual molecules, to track the motion of hydrogen atoms within free-based phthalocyanine molecules, and to follow resonance energy transfers between individual pigments. These results constitute an important step towards photonic measurements with atoms-scale resolution.

In this paper, we report the microscopic excitation and imaging of dielectric Mie resonators. The interaction of tightly focused vector beams with dielectric nanoparticles leads to exotic phenomena including multipolar excitation by displacement resonances, directional scattering, as well as superresolution imaging

Here, we take advantage of spectrally separated scattering and absorption resonance bands in Hyperbolic Meta-Antennas (HMA) to enhance the hot electron generation and prolong the relaxation dynamics of hot carriers. In this regard, for the realization of HMA, multilayered metal-dielectric structures based on gold/silica stacking layers are designed and fabricated to separate well-defined scattering and absorption bands. In contrast, conventional plasmonic (gold) nanodisk antennas (NDA) of thickness equivalent to that of total metal layers of an HMA are also realized as reference samples to distinguish the effect of multilayer HMA. First, we demonstrate the extended plasmon-modulated photoluminescence spectrum in HMA towards longer wavelengths due to its scattering spectrum in comparison to the corresponding NDA. Then, we demonstrate that the tunable absorption band of HMA controls and modifies the lifetime of the plasmon-induced hot electrons with enhanced excitation efficiency in the near-infrared region and broadens the utilization of the visible/NIR spectrum in comparison to NDA.

Plasmonic phenomena induce a highly concentrated electric field in small areas, manipulating the dynamic of microscopic objects. We report on a plasmonic structure that modulates the electric field by generating the propulsive motion of the nanoparticles. The system consists of two gold scalene trapezoids forming a planar V-groove. The designed geometrical configuration is suitable for an array configuration (circular or linear arrangement) that amplifies the output velocities of nanoparticles. The optical forces induced by the system enable the displacement of macroscopic objects with interesting applications in the biomedical and aerospace fields.

In monolayer Transition Metal Dichalcogenides (TMDs), the interplay between space-inversion and Time-Reversal (TR) symmetry defines the spin-valley degree of freedom: direct transitions at the ±K valleys are energetically degenerate but non-equivalent. Thus, engineering of TR symmetry naturally leads to the field of valleytronics, a new type of information technology that allows to manipulate data at the speed of ultrashort light pulses. However, all the methods that have been developed to date for the detection of a Valley Polarization (VP) are based on linear optics and suffer from severe limitations. In this talk, I will discuss a new method for the detection of broken TR symmetry and VP in TMDs based on nonlinear optics. I will show that the VP can be measured from a rotation in the polarization angle of the Second Harmonic (SH) signal emitted from the ±K valleys of a TMD monolayer. In addition, I will show signatures of valley polarization-electric dipole interference and demonstrate that this is a direct consequence of a phase-mismatch between the intrinsic (broken space-inversion symmetry) and valley (broken TR symmetry) terms of the second order nonlinear susceptibility.

One of the major challenges in nanophotonics is the direct measurement of the interaction of a nanostructure with a single fluorescent emitter at the nanometer level. Several approaches developed to this aim can be found in the literature. Recently, single molecule localization imaging, traditionally used for the study of biological samples, entered the nanophotonics realm opening new horizons. We report on the development of single-molecule fluorescence lifetime imaging microscopy (sm-FLIM), an innovative approach enabling the simultaneous measurement of the lifetime and the intensity of single-molecules densely labeling a nanostructured sample, with a field of view of 10 µm² , a spatial resolution of approximately 14 nm and a temporal resolution of approximately 50 ps. smFLIM enabled us to image, at the single molecule level, the Local Density of Optical States (LDOS, which is related to the inverse of the fluorescence lifetime) of dielectric nanoantennas and periodic arrays of hollow truncated plasmonic nanocones.

The different electron scattering in Al-doped ZnO (AZO) under intraband excitation was investigated through transient transmittance and reflectance. The electron-phonon scattering was probed to play a vital role in the hot carrier relaxation process while the electron-electron scattering also exhibits strong influence at high electron temperature.

Polaritons in two-dimensional layered crystals offer an effective solution to confine, enhance and manipulate terahertz (THz) frequency electromagnetic waves at the nanoscale. In this talk I’ll review recent results in the detection of dirac plasmon polaritons at THz frequencies, in hBN-encapsulated black-phosphorus field effect transistors through THz near-field photocurrent nanoscopy and in large area topological insulators through detectorless near-field digital holography.

We report the first-ever observation of optomagnetically-driven rotation of a magnetic particle, optically levitated inside a chiral hollow-core photonic crystal fibre (HC-PCF). Rotation of the optically biaxial particle causes a change in the transmitted power and ellipticity of a linearly polarised probe beam at 632.8 nm. HC-PCF offers a versatile platform for investigating the optomechanical response of levitated magnetic particles.

Fluoranthene and Pyrene (PAHs) airborne particles are well known for their mutagenic and carcinogenic properties. Manipulation of such nanoparticles below 100 nm makes it challenging due to their low polarizability and dielectric properties. Current optical nano-tweezer designs such as trench, slot and Hybrid Plasmonic Waveguides (HPWG) provides a strong gradient force for trapping, but they often have ≤ 50 nm gaps and have very low fabrication tolerances. In this work, we show the modeling of optical forces and sensitivity of different waveguide structures to sense large numbers of particles to monitor the Air Quality Index (AQI). To increase the trapping gaps and sensitivity in HPWG, we have designed them to use radiation modes of the dielectric waveguides. We call this phenomenon a “mode-lift”. Here we present the numerical and experimental results of industrially compatible integrated photonic sensors such as strip, slot, subwavelength grating (SWG) and HPWG used for measuring AQI.

Multipole expansions enable rapid numerical modeling of optical scatterer arrays, but choosing expansion centers is ambiguous. We derive optimal centers where multipolar spectra become unique, separately minimizing electric and magnetic quadrupole norms. This significantly reduces computations, benefiting differentiable solvers critical for machine learning photonics design. Analysis of dispersive mutual center positions provides insight into scattering and optical forces. Connections to optomechanics, and quantum/topological photonics are also hinted through links between the number of optimal magnetic centers and the topological metrics of resonant modes.

In microfluidic environments, particle transport is typically governed by slow diffusion near interfaces. However, by introducing localized fluid flow, it becomes feasible to actively transport suspended nano-objects within confined spaces. To achieve precise and dynamic control over fluid flow at the microscale, one promising approach is to leverage photothermal effects through the illumination of metallic or all-dielectric nanostructures. In this context, we explore the potential of manipulating the flow direction by adjusting the absorption characteristics of these metallic or dielectric nanostructures. By strategically designing the nanostructures and tailoring their absorption properties, we can exert precise control over the temperature distribution, thereby influencing the direction of fluid flow. This control over the flow direction opens up new possibilities for achieving desired transport capabilities within microfluidic systems.

Metallic nanoantennas have been studied as efficient coherent phonon generators and detectors, harnessing their characteristic optical absorption and polarization dependence of the optical modes. The ability to control the excitation of phononic modes depends on the properties of the multiple optical resonances of the system. Lately, it has been made possible to optimally excite and detect phonon modes via plasmon resonances at the same optical frequency using chiral nanostructures and circularly polarized light. However, torsional modes remain elusive in nanophononic studies. In this work we present a simple system composed of two coupled bars, where torsional mechanical modes can be excited using light with null angular momentum. The twisting of the phononic mode is provided by the peculiar symmetry of the mechanical eigenmode due to the interaction of the bars via either the substrate or a central connector. We will present a complete theoretical analysis of the phononic and plasmonic modes, their surface deformation field and electromagnetic field profiles.

Implementation of metasurface scanning for directional beam steering and metasurface arrays on imaging sensors are used to achieved 3D light Detection and Ranging (LiDAR) with impressive imaging performances. Our works show that metasurfaces have relevant industrial applications in 3D sensing, way beyond the basic usage of metalenses for imaging or point-cloud projection.

Nanophotonic devices for structural color generation based on plasmonics are usually built using the archetypal noble low loss metals Au and Ag, which are scarce and expensive. In this work, we show how underexplored p-block elements such as Bi or Sb in spite of being lossy, are promising alternative plasmonic materials that yield low-cost, sustainable and high purity colours. First, we demonstrate how Bi can be successfully nanostructured in the form of both gap-plasmon metasurfaces and metal/insulator/metal Fabry-Perot cavity colors, outperforming the colour purity achievable with traditional low loss metals. Second, using thin cavity structures, we explore their color performance on industrially important substrates such as silicon or steel directly as the back reflector. The results show high purity and environmentally robust vivid colors, suitable for cheap, outdoor, and daylight-friendly macroscopic coloring.

This contribution discusses the role of hexagonal Boron Nitride (hBN) as a host for photon emitters. In this study we employ gallium ion implantation to create emitters within hBN. Gallium ions are found to be optimal for generating many emitters, when both the ion energy and fluence are carefully controlled. Post-irradiation thermal annealing induces defect transmutation, providing spectral tunability to the emitters. Together with Focused Ion Beam (FIB) implantation, allowing for nanoscale defect positioning, it is possible to precisely pattern multiple photon emitters at various optical frequencies on one platform. Overall, the research highlights hBN potential in advancing quantum technologies.

We image the micro-photoluminescence of single self-assembled chains of CdSe nanoplatelets. Some portions of a chain show collective fluorescence intermittency, with around 30 platelets blinking at the same time. This effect is explained and modelled as Förster-Resonant Energy Tranfer (FRET) funneling all the excitons from a chain portion to a single blinking quencher.

We will demonstrate two methodologies for the retrieval of wavefront and polarization characteristics within optical fields. The first method offers a digital analog to Stokes polarimetry, requiring only four measurements, as opposed to the conventional six. Here we make use of a Polarization Grating (PG) together with a Digital Micro-mirror Device (DMD) to introduce a phase retardance between orthogonal polarization states to reconstruct both phase and polarization. The second approach leverages the concept of the transport-of-intensity, which capitalizes on the relationship between observed energy propagation in optical fields and their wavefront properties. To demonstrate the effectiveness of these techniques, we illustrate their application in spatially resolving exotic polarization structures, including metasurfaces, liquid crystal devices, and chiral materials.

We demonstrate the coherent manipulation of the spatial and temporal properties of ultrashort pulsed laser beams to generate wave packets that trace helical trajectories in space-time. This is achieved by introducing a non-separable correlation between the beam’s frequency (related to its temporal structure) and its orbital angular momentum (that defines its spatial topology). The demonstration relies on a diffractive axicon grating to separate the frequencies of a pulsed beam into colinear radial rings which are then independently modulated with an azimuthal phase using a digital spatial light modulator. The all-digital setup allows to tailor the topological-spectral correlations, affording control over a range of beam properties, while more complex correlations realize exotic space-time wave packets with extended beam dynamics. These unique beams open new horizons in ultrafast light-matter interactions, microscopy and multiplexing.

Fluorine-doped Indium Oxide (IO) nanocubes separated by nanometric gaps constitute a versatile system hosting high-quality mid-infrared plasmons with potential application in optoelectronics and light harvesting. In this theory-experiment combined work, we predict large tunability of these hybridized plasmon modes by controlling the gap size and the dimensionality of the gap region. We confirm this prediction through Electron Energy-Loss Spectroscopy (EELS) measurements performed in a Scanning Transmission Electron Microscope (STEM). Our theorical-experimental results elucidate the influence of gap geometry on the coupled plasmons and field concentration in doped IO nanostructures, and further suggest exciting applications in plasmonic sensing and surface-enhanced spectroscopies.

In this work, we use monocrystalline LaPO4:Eu nanorods as polarized luminescent probes. By distinguishing between emission peaks originating from magnetic and electric dipole transitions, we can derive the three-dimensional orientation of the nanorods through measurements of their polarized luminescence. This spectroscopy-based orientation analysis can furthermore be used to characterize microfluidic media, as the collective orientation of nanorods is directly related to flow conditions they are subjected to. Using a confocal microscope, we can locally determine their collective orientation which provides a direct measure of the shear stress. We demonstrate this method to map the shear stress profile in different microfluidic channel geometries and monitor the shear stress in an energy harvesting device.

In this work, we prepare plexcitonic nanoparticles composed by plasmonic nanoparticles, Au@Ag@mSiO2 nanorattles, and J-aggregates of TDBC cyanine dye to be used as ultra-efficient SERS-tags. The methodology used here allowed us to improve the colloidal stability of the plexcitonic nanoparticles. The optical properties have been characterised by UV-vis-NIR and Surface-Enhanced Raman Scattering (SERS) spectroscopies. Besides, finite-difference time-domain (FDTD) calculations revealed that the electromagnetic field is strongly confined into the J-aggregate deposited over the surface of the plasmonic nanoparticle at wavelengths near the upper plexciton. However, for the lower plexciton mode, the electromagnetic field decays through the J-aggregate/water interface. In summary, the plexcitonic nanoparticles showed high SERS efficiency for 532 nm and 633 nm laser lines, even reaching single-nanoparticle detection. The results obtained showed us the significance of strong coupling effect which might lead new possibilities for ultrasensitive biosensing and bioimaging.

Quantum emitters in hexagonal boron nitride (hBN) crystals are optimal candidates for the observation of single photon emission, but achieving control over their features is a challenging task. In this work, we present the deterministic generation of emitters with selected position and spectral features with a method that combines ion implantation and annealing of the sample. With this method, we even achieved control over the density of emitters. Such control is a fundamental step towards the engineering of emitter ensembles that can be readily embedded in Van der Waals heterostructures and advanced quantum systems.

Highly anisotropic crystals have recently attracted considerable attention due to their ability to support polaritons with unique properties, such as hyperbolic dispersion, negative phase velocity, or extreme confinement. In particular, the biaxial van der Waals semiconductor α-phase molybdenum trioxide (α-MoO3) has received much attention due to its ability to support in-plane hyperbolic phonon polaritons (PhPs) —infrared (IR) light coupled to lattice vibrations in polar materials with ultra-low losses, offering an unprecedented platform for controlling the flow of energy at the nanoscale. In this talk, we will show experimental demonstrations of the unique behavior of PhPs in these crystals, including the visualization of anomalous cases of the fundamental optical phenomena of refraction and reflection, and the exotic phenomenon of canalization, in which PhPs propagate along a single direction with ultralow losses.

Photo-induced Force Microscopy (PiFM) offers a promising alternative to traditional scanning near-field optical microscopy for subwavelength imaging. PiFM's key advantage is its fully mechanical detection through the Atomic Force Microscope (AFM) cantilever, simplifying the setup by eliminating the need for optical detectors and complex interferometric techniques. However, PiFM typically requires laser modulation at the AFM cantilever's intrinsic frequency, which can be challenging in the visible and near-infrared ranges, often involving Acousto-Optic Modulators (AOMs) that introduce a wavelength-dependent laser steering. Our innovative setup eliminates the need for realignment, making PiFM a valuable tool for near-field spectroscopy in the visible and near-infrared spectral ranges.

This presentation will reveal the rules on selecting efficient plasmonic nanoheaters for biomedical proposes. Here, a size dependence of plasmonic nanoparticle optical heating will be disclosed. The continuous laser heating of gold nanoparticles is evaluated exploring theoretical and experimental approach. This study demonstrates the use of optimized plasmonic gold nanparticles as photothermal agent for photoacoustic imaging technic, for the inactivation of yeast and for in-vivo hyperthermia treatment of the Sarcoma-180. Our results pave the way for the rational use of plasmonic nanoheaters in photothermal applications.

Nanoscale resolved imaging and spectroscopy utilizing scattering-type Scanning Near-field Optical Microscopy (s-SNOM) or tapping AFM-IR (local detection of photothermal expansion) bypass the ubiquitous diffraction limit of light and achieve a spatial resolution less than 20 nm in the Infrared (IR) spectral range. Measurements have successfully demonstrated a wide range of analytical capabilities such as nanoscale chemical mapping and material identification, conductivity profiling and electric field mapping. The employed laser source critically determines the range of materials and phenomena which can be studied, motivating to continuously explore options to expand the accessible range, especially towards longer IR wavelengths. Here, we introduce a new tunable OPO laser source optimized for IR nanoscopy applications which covers a spectral range of 2-18 μm. To illustrate the capabilities of this laser source, we demonstrate correlative s-SNOM and tapping AFM-IR+ based imaging, point spectroscopy and hyperspectral imaging. Application examples for investigating phonon polaritons in hBN and MoO3 and determining the nanoscale chemical composition of a thin film polymer blend.

Nanophotonics opens up novel opportunities for frequency comb generation and frequency-comb based sensing. Beyond integration and compactness, it provides new powerful concepts of instruments for interferometry, three-dimensional imaging, molecular physics and spectroscopy. With selected examples, I will provide a summary of advances in the vibrant emerging field of integrated optics for frequency-comb applications.

Pump-probe spectroscopy is a well-established technique used to monitor the dynamics occurring in any state of matter, in timescales ranging from attoseconds to seconds and beyond. When performed at synchrotrons the technique offers probe with high repetition rate, wide scanning capabilities in terms of energy, spatial resolution at the nanometre scale, and elemental specificity. Recently, recognizing the impact and importance of such experiments across its science spectrum, Diamond with the strong support from the UK academic community, invested and deployed a novel laser source, PORTO, which can be used in various beamlines for pump-probe experiments. PORTO is a portable femtosecond laser system which has been used so far, for optical-pump and X-ray-probe absorption (XAS) and diffraction (XRD) experiments. Here we present its main characteristics and capabilities as well as its application in the areas of plasmonic photocatalysis and coordination chemistry, along with recent results about the ultrafast dynamics of hot electron ejection from plasmonic nanoparticles to semiconductor materials used in the field of plasmonic N2 photofixation.

Single photon emitters within hosts with high refractive indices suffer from low collection efficiencies due to total internal reflection at the host interface. This can be alleviated through shaping the local refractive index environment, specifically through forming open cavities and allowing matching between the emission mode in the host and travelling mode in air. We design micropillars around single photon emitters within aluminium nitride via electromagnetic simulations and show that the collection efficiency can be increased by an order of magnitude compared to the base case. We fabricate the designs through standard clean room procedures and confirm collection enhancement through confocal microscopy.

Plasmonic nanoheaters, have attracted great attention in nanomedicine, due to their ability to efficiently generate and control heat delivery at the nanoscale. There is a wide offer of nanostructures that provide with strong photothermal responses and heat delivery, however most of them deliver heat in a symmetric way or require a certain orientation with respect to the excitation source to perform adequately. Here, we will first present an overview of some novel designs, fully plasmonic or hybrid dielectric/plasmonic, capable of offering not only enhanced photothermal response but also directional heat delivery. The thermal enhancing mechanism rely on the excitation of either dipolar or anapolar modes, depending on the design [4]. In the rest of the talk, we will show some of our recent findings on the thermal performance of DNA origami-based structures, offering theoretical insights into their potential for photothermal therapy applications.

Janus nanoparticles, incorporating plasmonic materials, have become important in thermoplasmonics. Controlled by pulsed excitation lasers, these nanostructures transfer thermal energy through material-fluid interfaces, regulated by interfacial thermal conductance. Here, we will present our most recent results in revealing the influence of interfacial thermal conductance on the thermal relaxation of metal-polymer Janus nanoparticles that exhibit directional heat dissipation under pulsed illumination. In particular, we will discuss how neglecting the temperature dependence of thermophysical properties leads to an overestimation of the nanoparticle's temperature. We demonstrate the potential of gold/polymer semishell nanostructures as effective nanoheaters for photothermal therapies. Our findings can motivate the exploration of innovative strategies for efficient nanoheating platforms in temperature-controlled devices.

We demonstrated a novel depth sensing system that utilizes metasurfaces and Photonic Crystal Surface-Emitting Lasers (PCSELs), realizing structured light generation and facial recognition in monocular depth sensing. Our single-shot system projects approximately 45,700 infrared spots from a 297² μm² metasurface area, which is 233 times smaller than the commercial DOE-based dot projector used in the Face ID on iPhone. The proposed system provides a measured Field-of-View (FOV) of 158°. The system is lens-free and power consumption due to the utilization of PCSEL, reducing five to ten times of power compared to VCSEL-array based dot projectors.

Hexagonal SiGe alloys offer a group IV direct bandgap for integrated photonics, addressing the limitations of traditional silicon-based electronics. We have synthesized coaxial nanowire shells comprising direct bandgap hex-Ge/SiGe and hex-SiGe/SiGe Quantum Wells (QWs) around a wurtzite GaAs core. Time-resolved photoluminescence measurements demonstrate a 1 nanosecond radiative lifetime, proving direct bandgap emission. Photoluminescence spectra show the QW emission in between the emission of the well and the barrier material, indicating type-I band alignment. Measurements as a function of QW thickness demonstrate clear quantum confinement with emission up to room temperature for thick QWs. By changing the QW-thickness and the well composition, the emission could be tuned between 2000-3400 nm. The experimentally observed direct bandgap SiGe QWs with type-I band alignment are expected to be pivotal for the development of novel low-dimensional devices based on hex-Ge and hex SiGe.

Efficient integration of Quantum Emitters (QEs) with beam shaping and polarization encoding functionalities has always been on the agenda but heretofore remained elusive. Here, we proposed a general approach for designing chip-integrated single-photon sources with flexible control of photon polarization states and Orbital Angular Momenta (OAM), including the possibility for multichannel single-photon generation. The developed approach is based on meticulous design of QE-coupled anisotropic metasurfaces for outcoupling QE-excited diverging Surface Plasmon Polaritons (SPPs) into single-photon beams with desired properties. We have realized independent manipulation of the single photon Spin Angular Momentum (SAM) and OAM states by using anisotropic metasurfaces. Furthermore, we have demonstrated the generation of high-purity Linearly Polarized (LP) single-photon beams with arbitrary different OAMs and further extend to realize multiplexing of single-photon emission channels with orthogonal LPs carrying different topological charges. Our findings provide a promising approach for chip-scale control of quantum emission with versatile functionalities.

In this study, we showcase the innovative application of Orbital Angular Momentum (OAM) beams for precise manipulation of 2D material structures, emphasizing spatial and temporal control. Focusing on graphene and WS2, we illustrate the efficacy of OAM beams in manipulating the materials electrical properties. Additionally, we present a device—an optically controlled graphene Field-Effect Transistor (FET)—as a prime example of the practical implementation of this technique, highlighting its potential in advancing the field of optoelectronics and material science.

We just entered a new era of materials characterization, where atomic sensitivity can be achieved by plasmon-enhanced optical spectroscopy. During this talk you’ll hear about a new characterization method where nanoparticle-mediated electrical contacts can “squeeze” light in the device active material, providing an innovative non-destructive technique able to characterize various device materials changes in operando. We will discuss how we probed few hundreds oxygen vacancies drift in thin (~5 nm) dielectric films during device switching just by the aid of visible light, an approach that helped to identify the breakdown mechanisms upon cycling in memristive device and ultrathin ferroelectric memory devices (FeRAMs). Ypu will hear about the first characterization of nanoscale MoS2-based electrical switches at room temperature and in air, where we proved volatile threshold resistive switching due to the intercalation of metallic atoms (nanofilaments 1–2 Au atoms thick) from electrodes directly between Mo and S atoms.

I will present our recent experimental results with optical resonators made of various phases of matter, including plasma microcavities and liquid ones. In plasma microresonators, we demonstrate an ultrahigh Q optical microresonator with plasma inside. This plasma cavity might impact new types of plasma-based optical interconnects and electrically pumped ultracoherent-microlasers. In liquid-based resonators, we demonstrate a Fabry–Pérot resonator, where one of its mirrors is based on total internal reflection from a liquid phase boundary. As such, they can optically interrogate capillary waves and resonances at the liquid-air interface. Such FP cavities can serve as a new way to bridge between capillary waves in liquids and electromagnetic waves in optics while benefitting mutual resonance enhancement (capillary and optical). This is the first time that such resonators have been demonstrated.

Light transport through disordered media exhibits various behaviors depending on the disorder strength. Insight is gained on how light interacts with the medium by investigating the statistical properties of the scattering matrix. Historical results were obtained by considering non-resonant scattering systems. In this work, we present innovative numerical results using a microscopic description of systems entirely made out of point-like resonant scatterers. We access light transmission and energy storage in these systems. Their resonant behavior engenders strong frequency-dependent response to incident wavefronts which allows switching between transport regimes while fixing the scatterers density. We show that light can travel ballistically, diffusively or be localized, by only tuning the incident field frequency. The velocity of energy is affected by the resonant behavior of the scatterers, becoming dependent on the disorder strength. Our results suggest benefits in using fully resonant systems for applications aiming at maximal energy deposition within strongly scattering media.

Plasmonic-molecular systems are gaining interest as a platform to studying strong light-matter coupling effects, owing to small mode volumes of plasmonic modes and relatively small systems sizes (hundreds of atoms) enabling tackling them by the ab initio methods. In our work we use real-time TD-DFT method to study what modifications of the systems occur under strong coupling conditions, including plasmon redshift and molecular absorption quenching. We observe mixed transitions, i.e. ocurring when the initial and excited states are located in different subparts of the system, as well as the drastic modifications of the molecular oscillator when modeling the systems with the coupled oscillators model. We show how atomistic scale effects influence the coupling and how to tailor the polaritonic states to obtain desired features in the system.

Van der Waals (vdW) materials are at the core of modern optoelectronics and nanophotonics. However, relatively limited research attention is devoted to their giant optical anisotropy. Here, we demonstrate that the use of giant anisotropy leads to the next-generation integrated circuits and optical elements, determining the exact values of anisotropic dielectric permittivity tensor for the variety of vdW materials in the broad spectral range (250–1700 nm) using cross-validation of far- and near-field techniques, accompanied by first-principle calculations. Our results show high refractive index, transparency over the whole studied spectral range and giant optical anisotropy for all investigated vdW materials. Furthermore, we suggest applications of vdW materials for chiral optics and integrated photonics.

Experimentally, strong localization of electromagnetic waves in three dimensions has never been achieved, despite extensive studies. Moving away from the paradigm of disordered systems, we perform microwave transport experiments in planar aperiodic Vogel spiral arrays of cylinders with high dielectric permittivity. By characterizing the electromagnetic modal structure in real space, we observe combinations of long-lived modes with Gaussian, exponential, and power law spatial decay. This distinctive modal structure, not present in conventional photonic materials with periodic or disordered structures, is the cause of significant electromagnetic wave localization that persists even in a three-dimensional environment.

Vectorial optical fields have recently attracted significant attention due to their importance in sensing, imaging, light-matter interactions and controlling photonic responses of nanoparticles and nanostructures. In this respect, the interaction of polarised fields with chiral nano-objects is of particular interest because controlling directionality of scattering via chirality of light or nanostructures would open up new applications in nanophotonics and photochemistry. Here, a novel concept of rotating chiral dipoles is introduced to obtain the relationship between the directionality and the handedness of scattering fields and realize unidirectional chiral scattering. Through the engineering of multipole excitation in plasmonic helicoid nanoparticles, we systematically introduce and demonstrate, both numerically and experimentally, the rotating chiral dipole for highly-directional forward scattering of circularly-polarized light. This concept of rotating chiral dipoles may be important for designing scattering from nanostructures and optical nano-antennas.

Simple acoustoplasmonic resonators, such as nanobars and crosses, are efficient light-hypersound transducers. The excitation of hypersonic modes in these structures strongly depends on the spatial profile of the acoustic and plasmonic eigenmodes and the optical properties of the system's resonances. Lately, it has been made possible to selectively excite and detect phonon modes via plasmon resonances at the same frequency using chiral nanostructures and circularly polarized light. In this work we present a system that is composed of a metallic propeller-like structure, based in a three lobed perforated clover whose top face is twisted with respect to its bottom one. The presence of the twisting angle gives rise to the excitation of non-conventional phononic modes. We will present a complete theoretical analysis of the phononic and plasmonic modes, their surface deformation field and electromagnetic field profiles.

In the present work, we experimentally demonstrate a suspended tunable subwavelength nanobeam cavity based on our recently proposed advanced dielectric bow-tie design combining ultra-low mode volume and high Q-factor. The nanobeam cavity is efficiently coupled to waveguide ports, allowing full integration with the existing silicon photonic platform and mitigation of the detuning between the optical mode and quantum emitter, which inevitably appears in a coupled system of an emitter and cavity due to fabrication disorder. The tunability of the nanobeam cavity is achieved through nanoelectromechanical actuation using electrostatic comb-drive actuators. The proposed bow-tie nanobeam cavity supports a fundamental optical mode confined in solid in the telecom C-band with a normalized mode volume below 0.12 and Q-factor of 3500. By applying the voltage to the comb-drive actuators, we experimentally observe the dynamic reconfigurability of the cavity resonance wavelength within 11 nm. Our findings can open a new prospect for efficient and tunable nanodevices for enhanced light-matter interactions.

This work presents the conjugation of tumor-specific targeting ligands, folic acid, onto the surface of Conjugated Polymer Nanoparticles (CPNs) based on a common solar cell material (PTB7), which exhibits low nonspecific cell adhesion. The goal is to create near-infrared (NIR)-active theranostic probes capable of specifically targeting cancer cells. By adjusting the proportion of folic acid during the synthesis process, the targeting efficiency and singlet oxygen generation efficiency of the nanoparticles can be finely tuned.

We investigate the emergence and development of collective resonant effects in finite-size arrays of silicon nanoparticles. We focus our research on two different scenarios of collective resonances: the lattice resonant Kerker effect and the quasi-bound state in the continuum. In the coupled dipole approximation, the implementation of such resonances is explored depending on the number of particles in the arrays and the conditions of external excitation. The results of the work are important for the prediction and experimental observation of collective resonances in real finite-size structures.

Integrated photonic devices are at the basis of all-optical chips, essential ingredients for quantum information technology applications. In such devices, one of the key features relies on the control of the emission properties of integrated solid-state quantum emitters, most importantly, the spontaneous emission dynamics. In this way, one is able to control, for instance, the single-photon emission repetition rate and improve the coherence of the emitted quantum light, by reducing the spontaneous emission lifetime. We demonstrate the potential of nano-photonic devices characterized by a bio-inspired deterministic aperiodic structure, based on spiral geometries, as an on-chip platform for cavity quantum electrodynamics experiments. Aperiodic order, in particular, following spiral configurations, is present in natural systems where, for instance, the arrangements of leaves and seeds in plants follow Fibonacci series. The study of bio-inspired systems has attracted considerable interest in classical photonics, and we here implement such an approach to quantum photonics.

This work is dedicated to laser engineering of spherical resonant Mie-excitonic nanoparticles from layered materials, particularly Transition Metal Dichalcogenides (TMDC). The proposed approach leverages femtosecond laser ablation and fragmentation in liquids for the fabrication of water-dispersed ultra-stable spherical TMDC nanoparticles (NPs) of variable size (5 – 250 nm). Such nanoparticles demonstrate exciting optical and electronic properties inherited from the TMDC crystals, due to preserved crystalline structure, which offers a unique combination of pronounced excitonic response and high refractive index value, making possible a strong concentration of electromagnetic field in nanoparticles.

The fast manufacturing of centimeter-scale color printing and color filter arrays has been demonstrated by combining the concept of pixelated F–P cavities and the laser grayscale lithography technique. A centimeter scale F–P type color printing device with a spatial resolution of 5 μm × 5 μm and the 1/3-in. color filter arrays with resolutions higher than 1200 ppi were successfully fabricated. The proposed strategy can be used for colorful painting, flat panel displays, and so on.

Efficient manipulation of the valley degree of freedom in Transition Metal Dichalcogenide (TMD) monolayers at the nanoscale becomes very desirable for future developments in valleytronics. Resonant optical nanostructures are considered as potential tools in this endeavor; however, it is still unclear how they affect polarization properties of valley-specific monolayer emission. Here, we present a systematic experimental and numerical study that is aimed to bridge this gap. As a simple model, we consider a hybrid system where valley-polarized photoluminescence [1] or second harmonic from MoS₂ - monolayer is coupled with a plasmonic nanosphere. Through this study, we are not only aimed to refine the exciting simulation approaches for valleytronic devices, but also contribute to the deeper understanding of the rich physics of light-matter interactions at the nanoscale.

We propose a highly efficient Surface Plasmon Resonance (SPR)-based sensing device to detect various anaemic conditions in human blood. A thin aluminum (Al) metal-coated glass prism is used to excite surface plasmons. A high-dielectric constant material, TiO2, is used over Al-metal to enhance the sensitivity, and a layer of fluorinated graphene (FG) is used as a bio-recognition element to study biomolecular interactions. To demonstrate sensing application, an Al (30 nm)-based engineered plasmonic device with an optimized value of TiO2 (2nm) and functionalized with an FG layer is utilized to detect various hemoglobin (Hb) concentrations in human blood at a wavelength of 1550 nm. A value of sensitivity of 123 °/RIU and FOM 439 RIU-1 is observed for the proposed Al-TiO2-FG-based SPR sensor. The proposed sensing device can be used as a biosensor to detect anemia by accurately evaluating the level of Hb concentration, making it the best candidate for biomedical applications.

Photonic band gap crystals are being pursued for their great potential to govern the spontaneous emission of excited quantum emitters. Here, we study the radiative decay of excited PbS quantum dot nanocrystals inside 3D photonic band gap crystals made from silicon in the near-infrared. At frequencies just above the band gap, we observe 14x enhanced intensity from quantum dots inside the crystal compared to dots outside, indicative of strongly enhanced emission. Moreover, using time-resolved single photon counting, we observe fast non-exponential decay, which is consistent with probing an ensemble of quantum dots at varying depths in the nanopores, each experiencing a position-dependent enhanced local density of states.

Photocathodes are key elements in high-brightness electron sources and ubiquitous in the operation of large-scale accelerators. In this work, we propose the use of ultrafast laser nanostructuring techniques on copper photocathodes as a way to enhance the quantum efficiency of metallic photocathodes and enable their use in next-generation electron photoinjectors. When the surface is nanoengineered with patterns and particles much smaller than the optical wavelength, it can lead to the excitation of localized surface plasmons that produce hot electrons, ultimately contributing to the overall charge produced. To quantify the performance of laser nanopatterned photocathodes, we measured their quantum efficiency in a typical electron gun setup. Our experimental results suggest that plasmon-induced hot electrons lead to a significant increase in quantum efficiency, showing an overall charge enhancement factor of at least 4.5 and up to 25. We demonstrate laser nanopatterned plasmonic photocathodes outperform standard metallic photocathodes, and can be directly produced in-situ at the electron gun level in vacuum environments and without any disruptive intervention.

The current lack of transmissive photonic components in the extreme ultraviolet (XUV) spectral range poses a challenge for guidance and confinement at micro/nano-scale. In this study, we propose a novel theoretical approach for achieving guidance of XUV radiation by leveraging the electromagnetic linear response of Titanium-Aluminum-Titanium heterostructures within this spectral range. Our findings indicate that, due to the near-zero-index properties of aluminum and titanium, effective coupling of XUV radiation with plasma oscillations occurs in these heterostructures, enabling the excitation of diverse plasmon polariton modes. Our predictions, based on the semi-analytical solution of fully vectorial Maxwell’s equations, reveal that the aluminum thickness can efficiently modulate the dispersion profile of plasmon polariton modes, allowing for nanometer-scale confinement and micrometer-scale propagation length. These results hold promise for the development of future devices enabling advanced control and manipulation of XUV radiation.

We explore the evolving landscape of planar optics, driven by a growing demand for lenses with reduced thickness and enhanced super-resolution capabilities. Traditional methods face limitations in forward design, stemming from low discrete levels, periodic arrangements, and electromagnetic coupling between structures. To address these challenges, we present a lens design employing gradient topology optimization within the inverse design paradigm. Utilizing randomly arranged topology optimization under various critical conditions, our innovative approach yields supercritical lenses surpassing the highest Fourier frequencies. The objective is to attain subwavelength planar lenses with a 100 nm structural thickness. Considering practical manufacturing constraints, convolution is introduced during optimization, limiting the structure's minimum width and simulating real-world imperfections. Expanding functionality, we optimize a complex lens design for multi-band operation through a unified structure and correct chromatic aberrations using advanced methods. Furthermore, our analysis extends to spherical and off-axis aberrations, offering valuable insights into intricate lens design.

In this experimental study, we delve into the potential implementation of logic operations using the interference of propagating spin waves within a device comprising intersecting yttrium iron garnet waveguides with submicrometer width. Notably, we extend our exploration to incorporate phase-change materials as memory elements atop these waveguides. Our results underscore critical considerations in the design of magnonic nanodevices operating with short-wavelength spin waves, offering valuable insights for optimizing their performance in practical applications.